On 07/04/2022 11:27, Aswath Govindraju wrote: > Hi Roger, > > On 07/04/22 13:54, Aswath Govindraju wrote: >> Hi Roger, >> >> On 07/04/22 13:50, Roger Quadros wrote: >>> Hi Aswath, >>> >>> On 06/04/2022 16:52, Aswath Govindraju wrote: >>>> In AM62 SoC, the Designware Core USB3 IP is progammed to operate in USB2.0 >>>> only mode. Add driver for AM62 USB DWC3 Wrapper. >>>> >>>> Signed-off-by: Aswath Govindraju <a-govindraju@xxxxxx> >>>> --- >>>> >>>> changes since v2: >>>> - Removed the implementation of detecting the role from the wrapper >>>> driver and moved the implementation to using linux,extcon-usb-gpio >>>> driver for role detection. >>> >>> I'm a bit puzzled. So ID is managed by extcon-usb-gpio driver and >>> VBUS is managed by this driver. >>> >>> So who decides the USB ports state based on the below truth table? >>> >>> + /* >>> + * ID | VBUS | STATE >>> + * ----------------- >>> + * 0 | 0 | HOST >>> + * 0 | 1 | HOST >>> + * 1 | 0 | Disconnected (set mode valid to 0) >>> + * 1 | 1 | Device >>> + * >>> + */ >>> >>> If only ID signal is available to extcon-usb-gpio driver it cannot detect >>> the Disconnected state. We need to set mode valid to 0 for disconnected state. >>> >> >> Yes that is correct, the mode valid signal needs to be set when there is >> no cable connected. I am slightly confused on why 0-0 state is not >> considered disconnected? So, whenever VBUS is not high it should be >> disconnected right? Not necessarily. We might be in host mode (ID=0) and just not turned on the VBUS regulator (VBUS=0). Is this to be treated as disconnected? I'm just pointing out that things won't function anymore like the below code you had earlier as you have decoupled id_state from vbus_state. + /* detemine the role or find out if disconnect event */ + if (id_state) { + detect_role = DEVICE; + if (vbus_state) + connect = 1; + } else { + detect_role = HOST; + connect = 1; + } Now you are setting connect independently of ID. i.e. connect = vbus_state. Is that what you want? cheers, -roger >> > > Sorry, pressed the send button without reading everything properly. > > The implementation is such that the extcon-usb-gpio only updates the > role to the core driver based on ID pin state and the Mode valid bit is > set by the wrapper based on the VBUS state. > > Thanks, > Aswath > >> Thanks, >> Aswath >> >>> cheers, >>> -roger >>> >>> >>>> - Updated the binding documentation and example to reflect the same. >>>> >>>> >>>> drivers/usb/dwc3/Kconfig | 9 + >>>> drivers/usb/dwc3/Makefile | 1 + >>>> drivers/usb/dwc3/dwc3-am62.c | 446 +++++++++++++++++++++++++++++++++++ >>>> 3 files changed, 456 insertions(+) >>>> create mode 100644 drivers/usb/dwc3/dwc3-am62.c >>>> >>>> diff --git a/drivers/usb/dwc3/Kconfig b/drivers/usb/dwc3/Kconfig >>>> index c483f28b695d..cd9a734522a7 100644 >>>> --- a/drivers/usb/dwc3/Kconfig >>>> +++ b/drivers/usb/dwc3/Kconfig >>>> @@ -159,4 +159,13 @@ config USB_DWC3_XILINX >>>> This driver handles both ZynqMP and Versal SoC operations. >>>> Say 'Y' or 'M' if you have one such device. >>>> >>>> +config USB_DWC3_AM62 >>>> + tristate "Texas Instruments AM62 Platforms" >>>> + depends on ARCH_K3 || COMPILE_TEST >>>> + default USB_DWC3 >>>> + help >>>> + Support TI's AM62 platforms with DesignWare Core USB3 IP. >>>> + The Designware Core USB3 IP is progammed to operate in >>>> + in USB 2.0 mode only. >>>> + Say 'Y' or 'M' here if you have one such device >>>> endif >>>> diff --git a/drivers/usb/dwc3/Makefile b/drivers/usb/dwc3/Makefile >>>> index 2d499de6f66a..9f66bd82b639 100644 >>>> --- a/drivers/usb/dwc3/Makefile >>>> +++ b/drivers/usb/dwc3/Makefile >>>> @@ -42,6 +42,7 @@ endif >>>> # and allyesconfig builds. >>>> ## >>>> >>>> +obj-$(CONFIG_USB_DWC3_AM62) += dwc3-am62.o >>>> obj-$(CONFIG_USB_DWC3_OMAP) += dwc3-omap.o >>>> obj-$(CONFIG_USB_DWC3_EXYNOS) += dwc3-exynos.o >>>> obj-$(CONFIG_USB_DWC3_PCI) += dwc3-pci.o >>>> diff --git a/drivers/usb/dwc3/dwc3-am62.c b/drivers/usb/dwc3/dwc3-am62.c >>>> new file mode 100644 >>>> index 000000000000..5700258c8deb >>>> --- /dev/null >>>> +++ b/drivers/usb/dwc3/dwc3-am62.c >>>> @@ -0,0 +1,446 @@ >>>> +// SPDX-License-Identifier: GPL-2.0 >>>> +/* >>>> + * dwc3-am62.c - TI specific Glue layer for AM62 DWC3 USB Controller >>>> + * >>>> + * Copyright (C) 2022 Texas Instruments Incorporated - https://www.ti.com >>>> + */ >>>> + >>>> +#include <linux/init.h> >>>> +#include <linux/interrupt.h> >>>> +#include <linux/irq.h> >>>> +#include <linux/kernel.h> >>>> +#include <linux/module.h> >>>> +#include <linux/platform_device.h> >>>> +#include <linux/workqueue.h> >>>> +#include <linux/mfd/syscon.h> >>>> +#include <linux/of.h> >>>> +#include <linux/of_device.h> >>>> +#include <linux/pm_runtime.h> >>>> +#include <linux/clk.h> >>>> +#include <linux/regmap.h> >>>> +#include <linux/devm-helpers.h> >>>> +#include <linux/pinctrl/consumer.h> >>>> + >>>> +/* USB WRAPPER register offsets */ >>>> +#define USBSS_PID 0x0 >>>> +#define USBSS_OVERCURRENT_CTRL 0x4 >>>> +#define USBSS_PHY_CONFIG 0x8 >>>> +#define USBSS_PHY_TEST 0xc >>>> +#define USBSS_CORE_STAT 0x14 >>>> +#define USBSS_HOST_VBUS_CTRL 0x18 >>>> +#define USBSS_MODE_CONTROL 0x1c >>>> +#define USBSS_WAKEUP_CONFIG 0x30 >>>> +#define USBSS_WAKEUP_STAT 0x34 >>>> +#define USBSS_OVERRIDE_CONFIG 0x38 >>>> +#define USBSS_IRQ_MISC_STATUS_RAW 0x430 >>>> +#define USBSS_IRQ_MISC_STATUS 0x434 >>>> +#define USBSS_IRQ_MISC_ENABLE_SET 0x438 >>>> +#define USBSS_IRQ_MISC_ENABLE_CLR 0x43c >>>> +#define USBSS_IRQ_MISC_EOI 0x440 >>>> +#define USBSS_INTR_TEST 0x490 >>>> +#define USBSS_VBUS_FILTER 0x614 >>>> +#define USBSS_VBUS_STAT 0x618 >>>> +#define USBSS_DEBUG_CFG 0x708 >>>> +#define USBSS_DEBUG_DATA 0x70c >>>> +#define USBSS_HOST_HUB_CTRL 0x714 >>>> + >>>> +/* PHY CONFIG register bits */ >>>> +#define USBSS_PHY_VBUS_SEL_MASK GENMASK(2, 1) >>>> +#define USBSS_PHY_VBUS_SEL_SHIFT 1 >>>> +#define USBSS_PHY_LANE_REVERSE BIT(0) >>>> + >>>> +/* MODE CONTROL register bits */ >>>> +#define USBSS_MODE_VALID BIT(0) >>>> + >>>> +/* WAKEUP CONFIG register bits */ >>>> +#define USBSS_WAKEUP_CFG_OVERCURRENT_EN BIT(3) >>>> +#define USBSS_WAKEUP_CFG_LINESTATE_EN BIT(2) >>>> +#define USBSS_WAKEUP_CFG_SESSVALID_EN BIT(1) >>>> +#define USBSS_WAKEUP_CFG_VBUSVALID_EN BIT(0) >>>> + >>>> +/* WAKEUP STAT register bits */ >>>> +#define USBSS_WAKEUP_STAT_OVERCURRENT BIT(4) >>>> +#define USBSS_WAKEUP_STAT_LINESTATE BIT(3) >>>> +#define USBSS_WAKEUP_STAT_SESSVALID BIT(2) >>>> +#define USBSS_WAKEUP_STAT_VBUSVALID BIT(1) >>>> +#define USBSS_WAKEUP_STAT_CLR BIT(0) >>>> + >>>> +/* IRQ_MISC_STATUS_RAW register bits */ >>>> +#define USBSS_IRQ_MISC_RAW_VBUSVALID BIT(22) >>>> +#define USBSS_IRQ_MISC_RAW_SESSVALID BIT(20) >>>> + >>>> +/* IRQ_MISC_STATUS register bits */ >>>> +#define USBSS_IRQ_MISC_VBUSVALID BIT(22) >>>> +#define USBSS_IRQ_MISC_SESSVALID BIT(20) >>>> + >>>> +/* IRQ_MISC_ENABLE_SET register bits */ >>>> +#define USBSS_IRQ_MISC_ENABLE_SET_VBUSVALID BIT(22) >>>> +#define USBSS_IRQ_MISC_ENABLE_SET_SESSVALID BIT(20) >>>> + >>>> +/* IRQ_MISC_ENABLE_CLR register bits */ >>>> +#define USBSS_IRQ_MISC_ENABLE_CLR_VBUSVALID BIT(22) >>>> +#define USBSS_IRQ_MISC_ENABLE_CLR_SESSVALID BIT(20) >>>> + >>>> +/* IRQ_MISC_EOI register bits */ >>>> +#define USBSS_IRQ_MISC_EOI_VECTOR BIT(0) >>>> + >>>> +/* VBUS_STAT register bits */ >>>> +#define USBSS_VBUS_STAT_SESSVALID BIT(2) >>>> +#define USBSS_VBUS_STAT_VBUSVALID BIT(0) >>>> + >>>> +/* Mask for PHY PLL REFCLK */ >>>> +#define PHY_PLL_REFCLK_MASK GENMASK(3, 0) >>>> + >>>> +#define DWC3_AM62_AUTOSUSPEND_DELAY 100 >>>> + >>>> +struct dwc3_data { >>>> + struct device *dev; >>>> + void __iomem *usbss; >>>> + struct clk *usb2_refclk; >>>> + struct work_struct work; >>>> + int vbus_irq; >>>> + int rate_code; >>>> + int connect; >>>> + struct regmap *syscon; >>>> + unsigned int offset; >>>> + unsigned int vbus_divider; >>>> +}; >>>> + >>>> +static const int dwc3_ti_rate_table[] = { /* in KHZ */ >>>> + 9600, >>>> + 10000, >>>> + 12000, >>>> + 19200, >>>> + 20000, >>>> + 24000, >>>> + 25000, >>>> + 26000, >>>> + 38400, >>>> + 40000, >>>> + 58000, >>>> + 50000, >>>> + 52000, >>>> +}; >>>> + >>>> +static inline u32 dwc3_ti_readl(struct dwc3_data *data, u32 offset) >>>> +{ >>>> + return readl((data->usbss) + offset); >>>> +} >>>> + >>>> +static inline void dwc3_ti_writel(struct dwc3_data *data, u32 offset, u32 value) >>>> +{ >>>> + writel(value, (data->usbss) + offset); >>>> +} >>>> + >>>> +static void connect_detect_work(struct work_struct *work) >>>> +{ >>>> + struct dwc3_data *data = >>>> + container_of(work, struct dwc3_data, work); >>>> + u32 vbus_state, reg; >>>> + int connect = 0; >>>> + >>>> + /* Read the status for VBUS valid register */ >>>> + vbus_state = dwc3_ti_readl(data, USBSS_VBUS_STAT); >>>> + vbus_state &= USBSS_VBUS_STAT_VBUSVALID; >>>> + >>>> + if (vbus_state) >>>> + connect = 1; >>>> + >>>> + /* Set or clear mode valid bit based on connect or disconnect event */ >>>> + if (data->connect != connect) { >>>> + reg = dwc3_ti_readl(data, USBSS_MODE_CONTROL); >>>> + if (connect) >>>> + reg |= USBSS_MODE_VALID; >>>> + else >>>> + reg &= ~USBSS_MODE_VALID; >>>> + >>>> + dwc3_ti_writel(data, USBSS_MODE_CONTROL, reg); >>>> + data->connect = connect; >>>> + } >>>> +} >>>> + >>>> +static irqreturn_t connect_detect_irq_handler(int irq, void *dev_id) >>>> +{ >>>> + struct dwc3_data *data = dev_id; >>>> + u32 reg; >>>> + >>>> + /* Clear VBUS interrupt always to aviod queuing up redundant work items */ >>>> + reg = dwc3_ti_readl(data, USBSS_IRQ_MISC_STATUS); >>>> + reg |= USBSS_IRQ_MISC_VBUSVALID; >>>> + dwc3_ti_writel(data, USBSS_IRQ_MISC_STATUS, reg); >>>> + >>>> + queue_work(system_power_efficient_wq, &data->work); >>>> + >>>> + reg = dwc3_ti_readl(data, USBSS_IRQ_MISC_EOI); >>>> + reg &= ~USBSS_IRQ_MISC_EOI_VECTOR; >>>> + dwc3_ti_writel(data, USBSS_IRQ_MISC_EOI, reg); >>>> + return IRQ_HANDLED; >>>> +} >>>> + >>>> +static int dwc3_ti_vbus_irq_setup(struct platform_device *pdev) >>>> +{ >>>> + struct device *dev = &pdev->dev; >>>> + struct dwc3_data *data = platform_get_drvdata(pdev); >>>> + int irq, ret; >>>> + >>>> + /* Get the misc interrupt */ >>>> + irq = platform_get_irq(pdev, 0); >>>> + if (irq < 0) >>>> + return irq; >>>> + >>>> + ret = devm_request_irq(dev, irq, connect_detect_irq_handler, IRQF_SHARED, >>>> + dev_name(dev), data); >>>> + if (ret) { >>>> + dev_err(dev, "failed to required IRQ #%d-->%d\n", >>>> + irq, ret); >>>> + return ret; >>>> + } >>>> + >>>> + data->vbus_irq = irq; >>>> + >>>> + return 0; >>>> +} >>>> + >>>> +static int phy_syscon_pll_refclk(struct dwc3_data *data) >>>> +{ >>>> + struct device *dev = data->dev; >>>> + struct device_node *node = dev->of_node; >>>> + struct of_phandle_args args; >>>> + struct regmap *syscon; >>>> + int ret; >>>> + >>>> + syscon = syscon_regmap_lookup_by_phandle(node, "ti,syscon-phy-pll-refclk"); >>>> + if (IS_ERR(syscon)) { >>>> + dev_err(dev, "unable to get ti,syscon-phy-pll-refclk regmap\n"); >>>> + return PTR_ERR(syscon); >>>> + } >>>> + >>>> + data->syscon = syscon; >>>> + >>>> + ret = of_parse_phandle_with_fixed_args(node, "ti,syscon-phy-pll-refclk", 1, >>>> + 0, &args); >>>> + if (ret) >>>> + return ret; >>>> + >>>> + data->offset = args.args[0]; >>>> + >>>> + ret = regmap_update_bits(data->syscon, data->offset, PHY_PLL_REFCLK_MASK, data->rate_code); >>>> + if (ret) { >>>> + dev_err(dev, "failed to set phy pll reference clock rate\n"); >>>> + return ret; >>>> + } >>>> + >>>> + return 0; >>>> +} >>>> + >>>> +static void dwc3_ti_enable_irqs(struct dwc3_data *data) >>>> +{ >>>> + u32 reg; >>>> + >>>> + /* enable VBUSVALID interrupt */ >>>> + reg = dwc3_ti_readl(data, USBSS_IRQ_MISC_ENABLE_SET); >>>> + reg |= USBSS_IRQ_MISC_ENABLE_SET_VBUSVALID; >>>> + dwc3_ti_writel(data, USBSS_IRQ_MISC_ENABLE_SET, reg); >>>> +} >>>> + >>>> +static void dwc3_ti_disable_irqs(struct dwc3_data *data) >>>> +{ >>>> + u32 reg; >>>> + >>>> + /* disable VBUSVALID interrupt */ >>>> + reg = dwc3_ti_readl(data, USBSS_IRQ_MISC_ENABLE_CLR); >>>> + reg |= USBSS_IRQ_MISC_ENABLE_CLR_VBUSVALID; >>>> + dwc3_ti_writel(data, USBSS_IRQ_MISC_ENABLE_CLR, reg); >>>> +} >>>> + >>>> +static int dwc3_ti_probe(struct platform_device *pdev) >>>> +{ >>>> + struct device *dev = &pdev->dev; >>>> + struct device_node *node = pdev->dev.of_node; >>>> + struct dwc3_data *data; >>>> + int i, ret; >>>> + unsigned long rate; >>>> + u32 reg; >>>> + >>>> + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); >>>> + if (!data) >>>> + return -ENOMEM; >>>> + >>>> + data->dev = dev; >>>> + platform_set_drvdata(pdev, data); >>>> + >>>> + data->usbss = devm_platform_ioremap_resource(pdev, 0); >>>> + if (IS_ERR(data->usbss)) { >>>> + dev_err(dev, "can't map IOMEM resource\n"); >>>> + return PTR_ERR(data->usbss); >>>> + } >>>> + >>>> + data->usb2_refclk = devm_clk_get(dev, "ref"); >>>> + if (IS_ERR(data->usb2_refclk)) { >>>> + dev_err(dev, "can't get usb2_refclk\n"); >>>> + return PTR_ERR(data->usb2_refclk); >>>> + } >>>> + >>>> + /* Calculate the rate code */ >>>> + rate = clk_get_rate(data->usb2_refclk); >>>> + rate /= 1000; // To KHz >>>> + for (i = 0; i < ARRAY_SIZE(dwc3_ti_rate_table); i++) { >>>> + if (dwc3_ti_rate_table[i] == rate) >>>> + break; >>>> + } >>>> + >>>> + if (i == ARRAY_SIZE(dwc3_ti_rate_table)) { >>>> + dev_err(dev, "unsupported usb2_refclk rate: %lu KHz\n", rate); >>>> + ret = -EINVAL; >>>> + goto err_clk_disable; >>>> + } >>>> + >>>> + data->rate_code = i; >>>> + >>>> + /* Read the syscon property and set the rate code */ >>>> + ret = phy_syscon_pll_refclk(data); >>>> + if (ret) >>>> + goto err_clk_disable; >>>> + >>>> + /* VBUS divider select */ >>>> + data->vbus_divider = device_property_read_bool(dev, "ti,vbus-divider"); >>>> + reg = dwc3_ti_readl(data, USBSS_PHY_CONFIG); >>>> + if (data->vbus_divider) >>>> + reg |= 1 << USBSS_PHY_VBUS_SEL_SHIFT; >>>> + >>>> + dwc3_ti_writel(data, USBSS_PHY_CONFIG, reg); >>>> + >>>> + /* Initialize a work queue */ >>>> + ret = devm_work_autocancel(dev, &data->work, connect_detect_work); >>>> + if (ret) >>>> + goto err_clk_disable; >>>> + >>>> + /* Read and set VBUS IRQ */ >>>> + ret = dwc3_ti_vbus_irq_setup(pdev); >>>> + if (ret) >>>> + goto err_clk_disable; >>>> + >>>> + pm_runtime_set_active(dev); >>>> + pm_runtime_enable(dev); >>>> + /* >>>> + * Don't ignore its dependencies with its children >>>> + */ >>>> + pm_suspend_ignore_children(dev, false); >>>> + clk_prepare_enable(data->usb2_refclk); >>>> + pm_runtime_get_noresume(dev); >>>> + >>>> + ret = of_platform_populate(node, NULL, NULL, dev); >>>> + if (ret) { >>>> + dev_err(dev, "failed to create dwc3 core: %d\n", ret); >>>> + goto err_pm_disable; >>>> + } >>>> + >>>> + /* Enable vbus irq */ >>>> + dwc3_ti_enable_irqs(data); >>>> + >>>> + connect_detect_work(&data->work); >>>> + >>>> + /* Setting up autosuspend */ >>>> + pm_runtime_set_autosuspend_delay(dev, DWC3_AM62_AUTOSUSPEND_DELAY); >>>> + pm_runtime_use_autosuspend(dev); >>>> + pm_runtime_mark_last_busy(dev); >>>> + pm_runtime_put_autosuspend(dev); >>>> + return 0; >>>> + >>>> +err_pm_disable: >>>> + clk_disable_unprepare(data->usb2_refclk); >>>> + pm_runtime_disable(dev); >>>> + pm_runtime_set_suspended(dev); >>>> +err_clk_disable: >>>> + clk_put(data->usb2_refclk); >>>> + return ret; >>>> +} >>>> + >>>> +static int dwc3_ti_remove_core(struct device *dev, void *c) >>>> +{ >>>> + struct platform_device *pdev = to_platform_device(dev); >>>> + >>>> + platform_device_unregister(pdev); >>>> + return 0; >>>> +} >>>> + >>>> +static int dwc3_ti_remove(struct platform_device *pdev) >>>> +{ >>>> + struct device *dev = &pdev->dev; >>>> + struct dwc3_data *data = platform_get_drvdata(pdev); >>>> + u32 reg; >>>> + >>>> + dwc3_ti_disable_irqs(data); >>>> + >>>> + device_for_each_child(dev, NULL, dwc3_ti_remove_core); >>>> + >>>> + /* Clear mode valid bit */ >>>> + reg = dwc3_ti_readl(data, USBSS_MODE_CONTROL); >>>> + reg &= ~USBSS_MODE_VALID; >>>> + dwc3_ti_writel(data, USBSS_MODE_CONTROL, reg); >>>> + >>>> + pm_runtime_put_sync(dev); >>>> + clk_disable_unprepare(data->usb2_refclk); >>>> + pm_runtime_disable(dev); >>>> + pm_runtime_set_suspended(dev); >>>> + >>>> + clk_put(data->usb2_refclk); >>>> + platform_set_drvdata(pdev, NULL); >>>> + return 0; >>>> +} >>>> + >>>> +#ifdef CONFIG_PM >>>> +static int dwc3_ti_suspend_common(struct device *dev) >>>> +{ >>>> + struct dwc3_data *data = dev_get_drvdata(dev); >>>> + >>>> + /* disable irqs */ >>>> + dwc3_ti_disable_irqs(data); >>>> + >>>> + clk_disable_unprepare(data->usb2_refclk); >>>> + >>>> + return 0; >>>> +} >>>> + >>>> +static int dwc3_ti_resume_common(struct device *dev) >>>> +{ >>>> + struct dwc3_data *data = dev_get_drvdata(dev); >>>> + >>>> + clk_prepare_enable(data->usb2_refclk); >>>> + >>>> + /* Enable irqs */ >>>> + dwc3_ti_enable_irqs(data); >>>> + >>>> + return 0; >>>> +} >>>> + >>>> +static UNIVERSAL_DEV_PM_OPS(dwc3_ti_pm_ops, dwc3_ti_suspend_common, >>>> + dwc3_ti_resume_common, NULL); >>>> + >>>> +#define DEV_PM_OPS (&dwc3_ti_pm_ops) >>>> +#else >>>> +#define DEV_PM_OPS NULL >>>> +#endif /* CONFIG_PM */ >>>> + >>>> +static const struct of_device_id dwc3_ti_of_match[] = { >>>> + { .compatible = "ti,am62-usb"}, >>>> + {}, >>>> +}; >>>> +MODULE_DEVICE_TABLE(of, dwc3_ti_of_match); >>>> + >>>> +static struct platform_driver dwc3_ti_driver = { >>>> + .probe = dwc3_ti_probe, >>>> + .remove = dwc3_ti_remove, >>>> + .driver = { >>>> + .name = "dwc3-am62", >>>> + .pm = DEV_PM_OPS, >>>> + .of_match_table = dwc3_ti_of_match, >>>> + }, >>>> +}; >>>> + >>>> +module_platform_driver(dwc3_ti_driver); >>>> + >>>> +MODULE_ALIAS("platform:dwc3-am62"); >>>> +MODULE_AUTHOR("Aswath Govindraju <a-govindraju@xxxxxx>"); >>>> +MODULE_LICENSE("GPL"); >>>> +MODULE_DESCRIPTION("DesignWare USB3 TI Glue Layer") > >